298 PROCEEDINGS OF THE ACADEMY OF [Mch., 



mediad, often crossing those of the opposite side and many of them 

 attaining a length in excess of the greatest width of the body. At 

 the base they are very coarse, but taper gradually to the tip, which 

 is recurved as an acutely pointed hook (fig. 4). Tn section they 

 are often flattened and seldom perfectly circular. The interior consists 

 of a core of soft colorless fibres which are enclosed in a firmer and 

 brittle sheath or shell of a more or less iridescent brown color. It is to 

 this structure that these spines owe their softness and fragileness, 

 the latter quality being so marked that large specimens almost invaria- 

 bly have all of them broken short off above the felt, leaving the latter 

 exposed over the entire median expanse of the back, and giving to 

 this species an aspect which has natui-ally led to its identification with 

 A. aculeata. 



The felt fibres arise in three tufts, one ventral, one between and 

 one dorsal to the dorsal setse bundles. In large specimens the felt 

 forms a uniform continuous layer nearly -J- in. thick and of a smooth, 

 compact texture. The fibres appear to be finer than in the two 

 specimens of A. aculeata available for comparison. They also have less 

 color, many of them being altogether dull and colorless while others 

 exhibit a slight greenish iridescence. 



The type is No. 20, Collection Acad. Nat. Sci., and was taken by 

 Dr. Benjamin Sharp on the beach at Nantucket after a storm. About 

 a dozen other specimens have been examined, coming partly from the 

 game place, partly from the collections of Mr. Vinal Edwards on No- 

 man's Land and from dredgings of the U. S. F. C. steamer Fish Hawk 

 in the deeper waters off the same region. The species has not been 

 taken in the course of the recent extensive dredgings of the Fish Hawk 

 and Phalarope, either in Vineyard Sound, Nantucket Sound, or Buz- 

 zard's Bay. Occasionally, it is brought up in lobster pots set in the 

 deeper waters off Noman's Land, and it is probably this species which 

 is said to be sometimes thrown up in great numbers during heavy 

 storms on the shores of Block Island. 



